2 * 0.1   
2 * 0.2        0

2 * 0.4        0
2 * 0.8        0
2 * 1.6        1
2 * 1.2        1

2 * 0.4        0
2 * 0.8        0
2 * 1.6        1
2 * 1.2        1

2 * 0.4        0
2 * 0.8        0
2 * 1.6        1
2 * 1.2        1

.....无限循环0011....

